GoRouter on Golang 1.5 will stop accepting connections when Proxy Protocol is enabled and a client connects without sending data

[keymon]

Note: This issue comes from this comment by @shashwathi

What

GoRouter recently added Proxy Protocol support by merging #126 . That PR uses the go-proxyproto library which is affected by this bug armon/go-proxyproto#1 when using Golang 1.5.

GoRouter uses Golang 1.5 so it is affected. When a client connects to gorouter with proxy protocol enabled but does not send any data, it will block gorouter and prevent it from accepting new connections.

Impact

• Go router does behave normally and accept multiple connections, until the issue is triggered.
• This issue happens only when Proxy Protocol is enabled, it does not affect the original behaviour.
• This issue happens only if the incoming connection doesn't actually send over any data.
  • when behind a Proxy which uses Proxy Protocol, it will always send the PROXY header.
  • normal HTTP clients will always send HTTP headers.

How to reproduce

As described in this comment by @shashwathi

Steps to reproduce this issue:

• Enable proxy protocol on gorouter
• Use telnet to establish a long lived connection to GOROUTER_IP:PORT but not not send any data
• You can use curl or telnet to establish another connection to GOROUTER_IP:PORT. If you are using curl you will notice your request just hangs.

When you disable proxy protocol and repeat the above steps, you will see that the gorouter accepts multiple connections on its port.

We have a failing test case on a branch in gorouter to demonstrate the same.

Root cause

The root cause is described in armon/go-proxyproto#1

Solution

Possible solutions are:

• Use Goland 1.6, which is not affected by the bug.
• Patch go-proxyproto to handle this situation, for example by timing out if no data is sent over. This approach has been implemented here

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this:

https://www.pivotaltracker.com/story/show/126232931

The labels on this github issue will be updated when the story is started.

[keymon]

We implemented the second option Patch go-proxyproto to handle this situation, for example by timing out if no data is sent over in this PR armon/go-proxyproto#4. We implemented this feature for go router in this branch

We will give some time upstream to discuss this PR, and if it is gets merged, we will update the code in GoRouter.

Otherwise, we can copy that to the gorouter codebase, as it is a fair small implementation.

Please let us know any thoughts or comments.